Why fuse on positive but not on negative?

[cszosler]

Hi to you All.
If I could, I did install fuse/breaker (auto reset) on positive, but due to restricted room in water sealed junction box and resistance to bending of the cables (welding cable 0 AWG), the only option is to fuse negative side of 1500W anchor winch. For cable sizing calculation total lenght was used from battery positive to winch and back to negative, in this circuit there is no ground conection to any other reciver, it is totaly independent circuit, only including (home made) chain couter which takes mA only.
Is "fused positive" an tradition/standard or there are other factors I'm ignorant of. Gratly obligated for shearing your wisdom with me.
Chez

[a64pilot]

If you fuse the negative side, if there is a short circuit, nothing is there to protect from a fire.
You want to fuse positive and do it as close to the battery as is practicable. If nothing else get a fuseable link to put in the positive side close to the battery.

[Reefmagnet]

No technical reason the positive side is fused, it's more a convention.

Edit: Whoa. Two different perspectives already lol. To expand, mixing different polarity fused circuits is bad, m'kay, but the risk of fire, explosion or doom doesn't increase if the negative side is fused vs positive on a circuit.

[goboatingnow]

The primary reason positive fusing take place, is based on a set of standard assumptions

(a) Faults paths are generally to other negative returns
(b) negative wiring is less protected then positive wiring so that contact with other returns are more likely
(c) negatives are often commoned, so that a combined fuse is useless.


Fuse positives

dave

[Maine Sail]

Originally Posted by goboatingnow

The primary reason positive fusing take place, is based on a set of standard assumptions

(a) Faults paths are generally to other negative returns
(b) negative wiring is less protected then positive wiring so that contact with other returns are more likely
(c) negatives are often commoned, so that a combined fuse is useless.


Fuse positives

dave

Bingo!!

[cszosler]

Originally Posted by a64pilot

If you fuse the negative side, if there is a short circuit, nothing is there to protect from a fire.
You want to fuse positive and do it as close to the battery as is practicable. If nothing else get a fuseable link to put in the positive side close to the battery.

This is it, why I did not think outside of the (sealed next to the winch) box?. Yes, I'll fuse at battery positive in battery locker, it will be moisture protected there. Thanks for opening my eyes, same as, after you open your umbrela rain drops stop. All The Best.
Chez

[Terra Nova]

Originally Posted by a64pilot

... You want to fuse positive and do it as close to the battery as is practicable...

This is correct.